Heretofore, the polymer true-sphere has been produced by a method of polishing a solid material, or by a method of pouring a melt into a mold to conduct solidification, or by a suspension polymerization method. Also, a method of producing a glass true-sphere by using a magnetic field is used. In the latter method, the true-spheres are produced by magnetically floating diamagnetic inorganic glass with a magnetic field of not less than 20 T, melting it through a laser beam, shaping into a sphere through surface tension and then cooling.
In the production method of the polymer true-sphere by polishing the solid material or by utilizing the mold, the size of producible sphere is not limited, but there are caused a problem of true-sphere accuracy, and a problem of residual strain by compression stress and solidification stress, so that the resulting spheres are not suitable for optical use. And also, the suspension polymerization method has drawbacks that the size of the producible sphere is less than 2 mm at maximum and the control of the size is difficult, or deformation is caused during the agitation. In the method wherein the glass magnetically floated in air is melted through the laser beam and shaped into spheres through surface tension, it is required to use a strong magnetic field (about 20 T) for floating. Although the magnetic floating is enabled at a relatively weak magnetic field by using a pressurized oxygen gas, since the heating and melting are carried out in the oxygen gas, if the floated body is particularly an organic substance such as polymers or the like, there is a possibility that the organic substance is decomposed or burnt.